George, for whom it was a second Festival winner - his first was Galileo in the 2002 Ballymore Novices' Hurdle - said: "After he made those two or three mistakes, I thought we would be doing well to get in the first four, and he just kept picking up again. I suppose he won by four lengths going away at Sandown [in the G1 Tolworth Hurdle] and without those mistakes he would have done the same today. But you can't knock him for what he's done - he's still an inexperienced horse.

"To give Noel [Fehily, who rode Summerville Boy] his due, he got beaten on him early on in the season round here and he said that day that none of those horses would ever beat us with a true-run gallop, and he was correct. The horse has taken a lot of switching off at home, as well. He's ridden by one of my best riders, an Indian lad called Singh, and he's absolutely made that horse. He told me he would win a Grade One."

Asked about what he thought might lie ahead for the horse, George replied: "I'm sure [owner] Roger Brookhouse and I will hatch a few plans but let's just enjoy today. He was very, very ready for today so whether that might just empty him a bit, I don't know, but we've done the job we needed to."

Roger Brookhouse, owner of Summerville Boy, said: "That feels very good! We thought the horse had a very good engine and we didn't think the ground would be a bother to him. You want to stay in this and he's certainly done it. He made a mistake at the second-last and the last and he still got back up."

The Sky Bet Supreme Novices' Hurdle provided heartbreak for Newmarket trainer Amy Murphy following Kalashnikov's (5/1) narrow second in the opening race of the Cheltenham Festival.

Kalashnikov was well positioned throughout the two-mile event and jumped the final flight in front under Jack Quinlan. However, Summerville Boy responded willingly to Noel Fehily's urgings up the punishing Cheltenham hill to score by a neck in a thrilling finish.

The Gordon Elliott-trained Mengli Khan (14/1) was a further one and three-quarter lengths back in third.

The disappointment of the race was 7/4 favourite Getabird for Willie Mullins, Rich Ricci and Ruby Walsh, who finished a well-beaten 11th.

Murphy, one of Britain's youngest trainers at 25 years old, commented: "I'm so proud of Kalashnikov. He travelled brilliantly throughout and he went through the ground as well.

"The hill can find plenty of horses out and he just tired up the hill. He winged the last and I was hoping that he would on, but Summerville Boy is a good horse, so we're happy to just finish second in a Grade One.

"He's been a superstar this season and I'm absolutely delighted with how things have gone and his performance today.

"He's a really exciting horse and that will be his final run of the year. To finish second in two Grade Ones and win a Betfair Hurdle is a brilliant season and he'll be an exciting horse for next season.

"We'll definitely go chasing next season and we're looking forward to that."

Kalashnikov's jockey Jack Quinlan added: "He has run a blinder. It's another superb effort and he travelled so well throughout.

"He will be even better on decent ground and we're looking forward to fences next season.

"We're extremely proud of him and he's a credit to the yard."

Jack Kennedy, rider of the third Mengli Khan added: "He's run a cracker. I think he'll be a better horse on a sounder surface as the ground might have just found him out at the end."